EPROM2.THD --- Copyright 1988 by Phil Wheeler An original compilation of Compuserve Model 100 Forum messages for use by Forum members only. The Model 100/102/200 are designed to accept an auxilary ROM. Several commercial ROM's are available (e.g., Super ROM and Ultimate ROM II) and have been proven popular -- and there are custom ROM burning services advertized. It is possible to "roll your own", and users here have done so. These messages discuss technical issues involved -- while EPROM1.THD focuses more on the application involved. Message range: 166981 to 167160 Dates: 4/4/88 to 4/8/88 Fm: SCOTT T. SCHAD 73720,1166 To: Stan Wong 70346,1267 Do you think there is sufficient demand that you could justify such a labor-intensive process for small quantities of chips? I had wondered how you adapted the eproms for the Molex socket...it looks like it would be an extremely delicate process. Actually, I've been pursuing a different line entirely. I've been storing files on the eproms in a Psion Organiser, and loading them back into my 102 on demand. It's such a nice solution to secure storage on the road that I'm sending Portable 100 an article about it in a day or so. The Psion has Xmodem protocol, so I guess I could even send .CO files if I had something like Xtel that can handle binary files. Fm: SCOTT T. SCHAD 73720,1166 To: Stan Wong 70346,1267 This is somewhat off the subject, but I'd like your comments on the feasibility/difficulty of making an adapter to permit two molex roms to reside in my 102. There seems to be enough room in the rom compartment, and it would really be convenient for me. But can you speculate on what roadblocks I might be up against if I were to attempt it? Fm: Stan Wong 70346,1267 To: SCOTT T. SCHAD 73720,1166 1) On the subject of the EPROM, Tandy sells an adapter board which you then solder the EPROM to. It looks exactly like the PCSG products you see advertised. The board is about $7.50. 2) As for programming the EPROMs, I have access to several programmers at work. Programmers for an IBM PC are about $250 and up. I have written a program called MOTOHX.100 in DL7 which converts an area of memory to Motorola S-Records for the EPROM programmer I use. It is intended primarily for .CO files. 3) I'll be glad to program EPROMs for you and others if we can work out the what and hows. I can supply the EPROMs and the Tandy adapters (or supply the reference if you want to get them). I just shudder at the soldering work because I'm a klutz (I don't do it often enough so I go through a large learning curve each time I get out the old "iron."). 4) Two roms may fit in the compartment but I'm not sure how to mechanize it except through the system bus. Someone has written a file called TWO.ROM or something like that describing how he put two roms in his M102. It required cutting traces and soldering of the main board . Fm: SCOTT T. SCHAD 73720,1166 To: Stan Wong 70346,1267 I guess I should read those Tandy catalogs more closely! That's suprising they sel l the small circuit board required. The soldering is so delicate I would be hestitant to try it too. TWO.ROM is now on my "look-up" list. But I would rather swap roms in and out intead of risking damage to the main board. Perhaps another approach is needed. How large an eprom can the Tandy accept? Are 64K possible? Could two roms be combined into one? I suppose that might border on copyright infringement, if two commercial roms were combined. It's just that I refuse to do without my CLEUSEAU rom but still need a macho text-formatter like T-Word. Maybe I'll just get the DISK POWER program in ram and forget about hardware mods. As you have indicated, making an eprom is one thing, but getting it to coexist with the M100 o/s is something else entirely. Fm: Ran Talbott 70506,60 To: Stan Wong 70346,1267 Getting a BASIC program to run from ROM _might_ be possible, but I doubt it, since the BASIC interpreter code is "swapped out" to access the option ROM. If you're concerned about the vagaries of soldering EPROMs into carriers, you should be able to find people who'll do it for 50 cents each, if not less. Fm: Ran Talbott 70506,60 To: SCOTT T. SCHAD 73720,1166 You could merge the two ROMs into one. You'd need a special adapter board that would allow you to hook up a switch to select one "virtual ROM" or the other. As long as you retain ownership of the original ROMs and don't use them in another machine, there's no problem with copyright if you make a new ROM that combines the two. This is legally equivalent to copying programs from a floppy to a hard disk for use on a PC. Selling or otherwise transferring the "combined" ROM _would_ be a copyright infringement (if you sold it as part of a package that included the original ROMs, it _might_ be legally OK: you'd have to ask a lawyer. Ethically, I'd have no problem with it, if I knew the buyer was using it the same way I had). If you signed any knid of license agreement for the ROMs, you may have given up some of your rights, so you'd have to check with a lawyer. Fm: Stan Wong 70346,1267 To: SCOTT T. SCHAD 73720,1166 The M100/M102 can only accept a 32Kx8 EPROM. This is the size of the Basic ROM. The size is dictated by the addressing limitation of the 80C85 processor. Since it is an 8-bit processor, it can only address 64K bytes of memory. Tandy chose to divide this into 32K RAM and 32K ROM. The EPROM I have been using is a 27C256 part which is a CMOS 32Kx8 (256K bits) part. There is a product called the SAFE from PG Designs which will hold up to 8 roms, 4 Tandy style and 4 EPROM style roms. It costs $129. It fits on the bottom of the M100 and doesn't take up much room. I now have two purchased roms (Cleuseau/ROM2 being one of them) and plan to add my own EPROMs. As far is combining other roms are concerned, if there is space left at the end of a commercial rom, it can be copied to the EPROM, and then your code added to the end of it. Copyrights would be a problem but for personal use I don't think anyone would complain. I have scheduled a low-priority project to copy commercial roms into EPROM for backup purposes. It drives me nuts to think that some of these roms I have may not be supported in the future and replacements hard or impossible to come by. Fm: Stan Wong 70346,1267 To: Ran Talbott 70506,60 You are right. I don't think a Basic program would execute directly from the option rom. What I had in mind was to store the Basic program in option rom, then read it into ram, adjust the line number addresses, make a directory entry, and then run it from ram. An alternative would be to find a compiler (probably on a PC) which would compile rom-able machine code. According to Phil Wheeler, typical PC Basic compilers assume a larger machine and include all sorts of overhead. Still, I'm sure that there is a commercial product out there that will do this. I wonder how PCSG and TS do it? Fm: SCOTT T. SCHAD 73720,1166 To: Ran Talbott 70506,60 Sounds to me like legally one would be in the clear. But I'm not sure I would want to swtich between roms to use them. Instant-on has its advantages. Fm: SCOTT T. SCHAD 73720,1166 To: Stan Wong 70346,1267 Is the PCSG "SAFE" the same item that Traveling Software calls the 8-Rom Pac? Software-switched, and all that? Fm: Paul Globman 72227,1661 To: SCOTT T. SCHAD 73720,1166 SAFE is made by PG Design Electronics (not PCSG). The TSI 8 ROM Pak is actually SAFE with five ROMs installed. Fm: Stan Wong 70346,1267 To: SCOTT T. SCHAD 73720,1166 The TSI 8-Rompack is the PGD SAFE with Sardine and TS-DOS installed. SAFE has 4-EPROM sockets and 4-Tandy style rom sockets. With the TSI version, Sardine occupies the 4-EPROM sockets and TS-DOS one of the Molex sockets. If you want to do your own EPROMs then you either need to forgo Sardine or make up an EPROM with the little circuit board I mentioned earlier. I prefer to try and use the SAFE EPROM sockets since you can reprogram the EPROM. In the Tandy-style rom socket, once soldered the EPROM is now useless if you want a change. The SAFE is electronically switched as you mentioned. There is a review SAFE.REV in DL13. I don't own one yet so my opinions are based upon ads and reviews. Fm: Stan Wong 70346,1267 To: SCOTT T. SCHAD 73720,1166 Back to your idea of a math rom, I can't gauge the market appeal for such an item but if you think that it's worth doing then I have some stuff that can help you (completed and in development). The issue in my mind right now is not IF it can be done but how slick you want it. Right now I don't see any way of coding the math routines in anything other than m/l. A Basic compiler for the M100 doesn't exist except that the TCOMP program might work. Another possiblity would be a Basic compiler for a Z80 machine. The resulting m/l code could then be inspected and cleaned up for the M100. I'm trying to figure out how the user would invoke the math functions from Basic. Everything I've thought of so far is sort of a kludge. The problem is to figure out a general purpose method that encompasses interactive Basic as well as programmed Basic. Ideally you would like to be able to embed the functions as part of a Basic expression. Fm: SCOTT T. SCHAD 73720,1166 To: Stan Wong 70346,1267 I getcha now. The SAFE is the way to go because it can take the standard eproms. I'll look for the DL review file. Fm: SCOTT T. SCHAD 73720,1166 To: Stan Wong 70346,1267 I've been "hacking" recently on an old HP86 desktop with a CP/M card installed. The card basically is just a Z-80 that takes over from the native BASIC-only O/S of the computer itself. Your idea of creating the code for a Z-80 and then cleaning-it up for the 8085 is quite interesting to me. Lots of C/PM assemblers and cross-compilers are out there, and I've even considered one other approach: there are more Z-80 Forth implementations that you can shake a stick at. Some support cross-compilation for 8085's, and turnkeying the code to strip out the un-needed part of the Forth kernel. I'm going to do some further checking on the "Forth" dimension before I come to my senses and realize machine language is the only way to attempt it. I don't know if this is of any interest to you, but I recently learned there is a product called "Media master" that can read/write over 200 different CP/M formats from a standard PC. It's $50 and I've got the address here somewhere. Working with the old CP/M system is just a "for grins" hobby of mine, but it has made be realize that computers may have since become more complicated than the HP86 and Tandy 102..but not necessarily more sophisticated. Those older guys packed a lot of m/l smarts into that 64K address space... Fm: Ran Talbott 70506,60 To: Stan Wong 70346,1267 Phil's right: PC-oriented products think that a ROM is something you use to boot your hard disk with, and 32K is a good size for a screen buffer. Back when I was thinking seriously about developing M100 products, I decided that the best way to start without a big investment was to use Software Toolworks' C compiler on my CP/M system. It produces 8080 assembler source, so you can fiddle with it if needed, and the code is supposed to be ROMable. Fm: Ran Talbott 70506,60 To: Stan Wong 70346,1267 There are a couple of possible paths for making "re-programmable" ROMs in the Tandy adapter. First, if the Vpp and CE lines are brought out to the adapter's "pins", you can make an adapter using a Molex socket to plug the chip into a standard programmer. Failing that, as long as the CE and OE lines aren't shorted on the board, you could use a test clip with a ribbon cable (and a DIP connector on the other end) to connnect the chip to a programmer. Fm: Stan Wong 70346,1267 To: SCOTT T. SCHAD 73720,1166 1) Media Master is a fine product which I use at work and at home. I have a DEC Rainbow copy and an IBM PC copy. The IBM PC copy is used to read Kaypro diskettes. It's worth the money ($40 for PC version). The company is Intersecting Concepts, Thousand Oaks, CA. I also own the Code Blue product. All are great products, very nicely done. 2) Ran Talbott has a better idea if you can generate 8080 code instead of Z-80 code. It should be more compatible with the 8085. 3) Forth is worth pursuing, especially if there is a way to cross-compile to the 8085. It's better to program in a high level language whenever possible. 4) As soon as I wrap up a couple of projects, I'll get back into the EPROM project again. For info on the SAFE, contact Paul Globman via email. Fm: Stan Wong 70346,1267 To: Ran Talbott 70506,60 Making an adapter consisting of a Molex socket with wires coming out to a 28-pin header was my original thought but I like your idea of a test clip/ribbon cable better. I'll have to check one of blank circuit boards I have to check if CE/OE aren't shorted. I'll try and find the parts I have (I put them away for now since I have shelved the EPROM project for the time being).